Keithley 7070, Instruction Manual

Page: 59 / 73

SERVICE INFORMATION
4-2
CAUTION
Failure to obser ve the f ollo wing precautions
could result in dama ge not co vered b y the
warranty:
1. The shield m ust be installed suc h that the
metal side is facing a wa y fr om the matrix
car d. Bac kwar d installation will cause PC
boar d connections to shor t out a gainst the
metal shield.
2. The jumper wire m ust be connected as
sho wn in or der to pr ovide cir cuit pr otection
fr om static disc har ge .
Figure 4-1. Removing the Rear Shield
4.4 TROUBLESHOOTING
4.4.1 Recommended Equipment
Table 4-1 summarizes the recommended equipment for gen-
eral troubleshooting. Note that a second Model 7070, used
as an extender card, will be necessary to gain access to the
board components for troubleshooting.
WARNING
Disconnect all e xternal equipment fr om the car d
bef ore tr oub leshooting.
4.4.2 Troubleshooting Procedure
Table 4-2 summarizes the troubleshooting procedure for the
Universal Card. Some of the troubleshooting steps refer to
the ID data timing diagram shown in Figure 4-2. Also, refer
to paragraph 4.5 for an overview of operating principles.
NOTE
The Model 7070 should be in the LOCAL mode
when troubleshooting.
Rear Shield
Mounting
Hole and
Standoff
(1 of 8)
Matrix Card
Chassis
Ground
Wire
Tab le 4-1. Recommended Troub leshooting Equipment
Description
Manufacturer
and Model
Application
5
½
-Digit DMM
Oscilloscope
Extender Card
Keithley 199
TEK 2243
Keithley 7070* Measure DC voltages
View logic waveforms
Allow circuit access
*A second Model 7070 will be necessary to access the card.
Table 4-2. Troubleshooting Procedure
Step Item/Component Required Condition Comments
1
2
3
4
5
6
7
8
9
10
11
TP2
TP1
TP3
TP4
TP5
TP6
TP7
TP8
TP9
TP10
U30-U41, pins 10-18
+6VDC
+5VDC
NEXT ADDR pulses
CLR ADDR pulse
ID data pulses
STROBE pulse
Relay data (128 bits)
CLK pulses
High on power up until
Þ rst STROBE sets
low.
Low with relay energized, high with relay
de-energized.
All voltages referenced to TP2 (digital
common)
Relay voltage
Logic voltage
Power up only (Fig. 4-2)
Power up only (Fig. 4-2)
Power up only (Fig. 4-2)
End of relay data sequence
Present when updating relays
Present during relay data or ID data
Power on safe ground
Relay driver outputs must be pulled up
through relay coil to operate.